The semiconductor integrated circuit (IC) industry has experienced rapid growth. Technological advances in IC materials and design have produced generations of ICs where each generation has smaller and more complex circuits than the previous generation. However, these advances have increased the complexity of processing and manufacturing ICs and, for these advances to be realized, similar developments in IC processing and manufacturing are needed. In the course of IC evolution, functional density (i.e., the number of interconnected devices per chip area) has generally increased while geometry size (i.e., the smallest component that can be created using a fabrication process) has decreased.
Pads used for various applications, such as probe and/or wire bonding (generally referred to hereafter as a bonding pad) often have separate requirements than other features of an IC. For example, a bonding pad must have sufficient size and strength to withstand physical contact due to such actions as probing or wire bonding. There is often a simultaneous desire to make features relatively small (both in size and in thickness). For example, in applications such as a complementary metal-oxide semiconductor (CMOS) image sensor, it is often desired to have one or more relatively thin metal layers, for example a metal layer of aluminum copper (AlCu) that is patterned to form a bonding pad and shield structure for cross-talk prevention. In one conventional example, a metal shield and a bond pad are the same thickness and are relatively thin. However, a problem with thin metal layers is that the bond pads formed in these layers may exhibit peeling or other defects. A need therefore exists to accommodate the various requirements of these features.